The research objective is to understand the regulation of juvenile hormone (JH) synthesis by the corpora allata (CA). The system studied is primarily the female reproductive cycle of the viviparous cockroach, Diploptera punctata, in which egg development is precisely controlled by cycles of JH synthesis. The project will continue to provide evidence for a dual control system, inhibitory and stimulatory. We will test the hypothesis that these controls are mediated by neurosecretory substance from the brain and show how factors in the internal environment act on the brain to regulate their release. A direct measurement of JH synthesis by the CA will be made using an established short term in vitro radiochemical method. The CA will be subjected to altered environments in vivo by transplantation, and in vitro by use of explanted tissue or extracts thereof, in order to establish pathways of control. Correlated morphological evidence for neurosecretory control will be sought in studies of the CA and neurosecretory tissues using several techniques including histochemistry and electron microscopy.